noun
one's own ground; one's own position; one's own half/area of the field
Used in sports (soccer, rugby, etc.) and military/strategic contexts to refer to the side or territory one defends. Often contrasted with 敵陣 (enemy territory).
サッカーでは、自陣でボールを奪われないように注意する。
In soccer, be careful not to lose the ball in your own half.
敵を自陣に引き込んでから反撃した。
They lured the enemy into their own territory and then counterattacked.